Telephone-exchange system.



F A. LUNDQUIST.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED 050.2. 1916.

1,%7?',O91. Patnted Aug. 27, 1918.

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APPLICATION FILED 050.2 ms. 1377991 Patented Aug 2?, 1918 2 SHEETS'SHEET 2 ms NDRRIS PETERS cn.. PHO10-LIYHD.,\VAEHING'IUFL l: c.

" line switch.

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FRANK A. LUNDQUIST, OF NEW YORK, N. Y., ASSIGNOR T WESTERN ELECTRIC COM- PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters iatent. Patgntefl Aug, 27, 1918.

Application filed December 2, 1916. Serial No. 134,576.

To all whom it may concern:

Be it known that I, FRANK A. LUNDQUIST, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This. invention relates to telephone exchange systems, and more particularly to those in which automatic switches are employed in extending connections from one line to another.

The object of the invention is the provision of means, actuated when a call has been abandoned owing to the busycondition of a predetermined number of the connecting circuits available to the calling line, for automatically testing the idle or busy conditionot said connecting circuits, and for automatically closing a signaling circuit as soon as one of said connecting circuits becomes idle.

In the drawings, Figure 1 shows a circuit arrangement for one form of the invention in which relays denote the condition of the connecting circuits; and Fig. 2 shows a circuit arrangement of a modification in which a switch hunts for an idle connecting circuit.

Referring more particularly to Fig. 1, denotes a calling station connected by the wires (5 and 7 to line wipers 1 and 2 of a for the same switch, arranged to wipe over contacts in which the test wires 4 of the-associated connecting circuits terminate. The primary magnet PM operates the line switch, which is otfthe rotary step-by-step type, in terrupting its own circuit at the contact 8. A test relay TR will have its armature held up by a projection 9 on the rotary ratchet of the line switch when the switch is in normal position, and operates to hold the contacts 10, 11 and 12, 13 closed when its armature is held up, but to open. said contacts and to close the contacts 13, 14; when its armature is retracted. A ringing relay BB is provided with a lever 17, shown in norn L211 position, but which may be moved so as to close contacts 15 and 16, by a pro1ection 18 on the wiper when said wiper has passed to the last contact in its bank. When so moved the lever 17 willbe locked in off-nor- The wiper 3 is a' test wiper line switch.

mal position by the engagement of a pin which it carries with a lug carried by the armature 19 of the relay RR. When the relay RE is energized, the attraction of its armature l9 restores the lever 17 and closes contacts 20. w

A non-numerical switch 21 is operated by the magnet SM and has contacts 22 in which terminate wires leading to the springs 16 of a group of line switches. The contacts 15 of a group are multipled at the point 23 so that any one of the switches in a group may be used in cooperation with the-non-ninnerical switch 21. Stepping magnet SM interrupts its own circuit, and, while its armature 2 1 is attracted, closes the contacts 25. A relay 5, associated with each connecting circuit 1,

will be held energized when its circuit is in use as thebusy condition of these circuits is denoted by a dead ground from a spring 14E of the line switch with which it is in use. The back contacts of the relays 5 of the circuits in each group are multipled :to the magnet SM of a switch 21.

The operation of the system is as follows: hen the receiver is removed from the hook at the station A a circuit is-completed from battery, through the winding of the relay LR, wire 7, station A, wire 6, through the winding of the release magnet RM, which is slow to release, to ground. The consequent energization of the relay LR closes a circuit from battery, front contact and armature of relay LR, through the winding of the primary magnet PM, contact 8, contact springs 10 and Y11 to ground. The energi- Zation of the release magnet RM allows the holding pawl 27 to engage the ratchet of the Magnet PM now steps the wipers to the contacts of the first connecting circuit. If this circuit is busy there will be a ground from the contact 14 of some other line over the test wire 4, which will hold up the test relay TRover the contacts 13 and 12, through thewinding of the relay TR, to; battery and ground. Magnet PM will con tinue to step until an idle connecting circuit, indicated by a potential other than ground on the wire 4L, is found. When such a circuit is found the holding circuit for the relay TR, is broken, and the consequent retraction of the armature of said relay opens at the springs 10, ,11 the circuit for the primary magnet so that the switch stops with its wipers resting on an idle connecting circuit. The call may now be completed in the usual manner, it being noted that the release magnet RM will hold up while impulses are sent, as it is slow to release. At the end of the conversation the calling party breaks at his switchhook a circuit for the relay RM, which thereupon deenergizes and moves the holding pawl 27 from the ratchet of the line switch. The switch is thereupon restored by a spring (not shown) to its normal position at which time the arm 9 is brought up against a stop 28- and engages the armature of relay TR so as to hold the springs 10 and 11 closed in readiness for the next call.

It all the associated connecting circuits 4; are busy the wipers will he stepped to the last contact, at which time lever 17 will be operated in the manner previously described to close the springs 15, 16, and a busy tone will be placed on the calling line from ground at the secondary of the transformer Be, wiper 1', wire 7, station A, wire 6, through the winding of the relay RM to ground. Upon hearing this busy tone the calling party hangs up his receiver and the line switch is restored in the'usual manner, leaving the lever 17 locked in off-normal position.

hen the contacts 15 were closed an operating circuit for the switch 21 was partially closed from ground, contacts 15 and 23, armature 2%, through the winding of the magnet SM to the back contacts of the relays 5. As long as all the connecting circuits 1 are in use the relays 5 will be energized alnl'l'l'iis circuit will be incompleted. As soon as any line 4; becomes idle the deenergization or its relay 5 will complete the circuit from battery, through the armature and back contact of the relay 5 for the mag-,

net SM. The magnet SM 'will thereupon stop its wiper ver the contacts 22 until it finds the one associated with the contact 16 of the calling line, atiwhich time a circuit will be closed from ground, through the winding otthe' ringing relay RR, which is slow to release, lever 17, contact 16, terminal 22, wiper of the switch 21, sprin 25, to battery and ground. The consequent energization of the relay RRapplies ringing current from the generator 26 through the contact springs 2.0 to the subscribers line. The relay RR also breaks its own circuit by the restoration of the lever 17 and breaks the tacts 20' removin the 17111 111 current and.

7 C D D the system is restored to normal. The calling subscriber may now initiate another call with the knowledge that he will find an idle connecting circuit.-

If desired, the switch 21 and the mechanism associated therewith, including the contacts 15 and conductors leading thereto, may be omitted and the conductor extending from the fixed contact 16 may be connected to the conductor joining the fixed contacts of the relay 5. The system as thus modified will operate to signal the waiting subscriber in the same manner as by employing switch 21, but if a plurality of subscribers are waiting, all will be signaled, whereas if the switch 21 is employed only the first waiting subscriber will receive the signal.

Inthe modification shown in Fig. 2, the wires 206 and 207 lead from the calling line to the wipers 202 and 203 of a line switch, which is also of the step-by-step rotary type. ires 205 represent talking conductors which terminate in contacts associated with wipers 202 and 203. YVires 201 are the test wires associated with these connecting circuits and terminate in contacts associated with the test wiper 201. As the two line switches shown are of the same construction, the description is applicable to either. The switch is operated by a stepping magnet 208 which interrupts its owncircuit at its armature 209 and moves the switch by the engagement of a pawl 210 with a rotary ratchet 211 on the switch shaft. A holding pawl 21.2 normally engages the ratchet teeth but will, when the release magnet 21% is energized, be removed from such engagement so as to allow the switch to be restored under the action of the spring 218. A projection 215 on the ratchet holds the contact 216 open when the switch is in normal position, but allows it to close on the first step. A test relay 217 will be mechanically locked when energized by a: catch 218 which engages with a pin in the armature of relay 217. lVhen so held up the springs 219 will be open.

In this modification a non-numerical switch 220, having in its banks multiples ol the connecting circuit test wires 20%, is used to find an idle connecting circuit in place of the relays 5 of the modification shown in Fig. 1. The switch 220 is operated by a stepping magnet 221 which interrupts its own circuit at its armature 222. Another non-numerical switch has terminals 226 associated with ringing relays 227 in the group of line switches with which the connecting circuits 205 are associated. The switch 226 is -operated by a stepping magnet 224 which also interrupts its own circuit.

When a calling party removes his receiver from the ,switchhook at the station connected to wires 206 and 207 he completes a circuit from battery, through the winding of slow relay 228, back contact and inner armatureof relay 227, wire 206, through the telephone instrument of the calling line, wire 207, outer armature and back contact of relay 227, through retardation coil 229 to ground. The consequent energizationof relay 228 completes a circuit from battery, armature and front contact of relay 228,

winding of stepping magnet 208, armature- 209, contacts 219 to ground. The magnet 208 steps the wiper of the line switch until an idle connecting circuit is found, at whichcuit. The call may now becompleted in the,

usual manner, it being noted that the relay 228 is made slow so as to be held up during the sending of impulses. 1

At the close of the conversation the circuit for the relay 228 is broken at the switchhook of the telephone instrument of the calling line. Relay 228 in retracting its armature closes a circuit for the release magnet 214 from battery, armature andback contact of relay 228, through the ,windingof the magnet 214, contact 216 to ground. The energization of the relay 214 removes the holding pawl 212 from engagement with the ratchet 211 and the switch is restored. lVhen the switch reaches normal a projection 232 on the ratchet 211 engages the catch 218 so as to unlock the armature of relay 217, thus allowing the closure of springs 219, and the switch is readyfor the next call.

hen all the connecting circuits 205 are found busy the magnet 208 steps the: wipers of the line switch to their last position- A a circuit is now completed from ground, contact 234, wiper 201 in its last position,

- through the winding of the relay 233 to battery and ground. A busy tone is now placed onthe calling line from ground, through the secondary of the transformer Be, wiper 202, wire 206, telephone instrument (not shown), a wire 207, wiper 203, to battery and ground.

The calling party now replaceshis receiver on its hook and the switch is restored in the manner previously described I The relay 233, being slow to release, will hold up until the switch has returned its wipers to normal, at which time a locking circuit for it will be completed from grounded battery, through the winding of relay 233, its left armature. and front contact,

contact spring 235, wiper 201, spring 234 to ground. When the relay 233 was energized it completed a circuit from battery, outermost armature and contact of relay 233,

through the winding of slow relay 223, winding of stepping magnet 221, armature222,"

wiper of switch 220, wire 204, to the test energizes and the switch 220 stops.

. nec'tingcircuit which has become idle. At

this time no ground being found on the terminals of the wires 204, the magnet 221 de- The re lay 223, which held up during the operation of the switch 220 as it is slow to release, now

denergizes and completes a circuit from battery, middle right-hand armature and contact of relay 233, armature and contact of relay 223,I through the winding of the magnet 224, armature 235, contact and armature of relay'225 ,toground. The magnet 224, interruptingits circuit at its armature 235, steps the wiper of the switch 226.0ver

the contacts of thewires leading to the relays 227 of the line switches, in the group using the connecting circuits 205. When a switch is found which has been used in a connection which was not completed owing to the busy condition of all the associated connecting cir'cuits,-a circuit will be completed from battery, innermost right-hand armature and contact of relay 233, through the winding of slow relay227, wiper 'o't switch 226, through the winding of relay 225 to ground. The consequent energization of the relay 225 opens at its armature and back contact the circuit for the :magnet224, which deenergizes and stops the switch 226 with its wiper resting on the terminal asso-' ciated withfsuch aline. t The relay 227 is also energizedlover the 1 circuit just traced and applies ringing cur j, rent from. the generator 236, through thefront contact and-inner armature of'relay; 227, wire 206, ringer of calling station (not shown), wire 207 outer armature'and front contact of relay 227 to the generator 236. The inner armature of relay. 227, in pulling up, opened-at-the contact 225 the holding circuit. of the relay 233 which. releases-- slowly. In denergizing the relay 233 breaks at its innermost right-hand armature and contact the. circuit for. the, relay 227. The relay 227 now retracts its armature, removing the ringingcurrent from the calling lineand the system is now in normal position; The calling subscriber may now ini tiate another call with the knowledge that one of the connecting circuits 205 is idle.

Since the connecting circuits 4 in Fig. 1 t and 205 in Fig. 2 may lead either to an oper ators position in a semi-automatic system or to a selector switchain a full automaticzsystern, only the terminals in the banks of the lineswitcheshavebeen shown. I

What is claimed is: -1. In a telephone-:exchangesystem, telephoneklines, a group of connecting circuits,

means for extending a calling line to an idle connecting circuit, signaling means asso ciated with said telephone lines, means for automatically COIIHGCtHIg said signaling means to a callin =subscriberslinewhen all of said circuits are busy and means auto-- inatically operated as soon asone of said circuits becomes-idle to llifO'IIll' said calling subscriber of suclr a fact;

2; In a telephone exchange system, the" combination with telephone lines; connecting circuits a -nd means for automatically extending a call-ingl'nie to'an idle connecting circuit', of a signaling circuit: including said calling line, auxiliary automatic testing means operated if apredetermined num ber of said connecting circuits are busy, and means for automatically closingsaid signaling'circuit when one of saidvbusy connecting circuits becomes idle.

3. In a telephone exchange system, the combination withtelephoiie li'iies=,--connecting circuits, means for: automatically extending a calling line to an idle connecting circuit and" means automatically operated if a predeterminednumber of th'e connecting circuits are busy for projecting signaling current of one character over the calling line, of asignaling circuit" including said telephone line, and" auxiliary automatic testing means constructed and arranged to close said signaling circuitwhen one ofsaid connecting circuits becomes idle.

4. In a telephone exchangesystem', the

combination with telephone lines, connecting circuits, means for automaticallyextending a calling line to an idle connecting circuit and means automatically operated 'if' a predeterminednumber of said connecting cir-- cuits are busy for projecting. signaling current of one character over the calling line,-

of a signaling; circuit including, said" calling line, and auxiliaryautomatic testing in'eans" automatically rendered active: if said pre determined number of connecting circuits are busy, said testing meaiisb'eing construct;

ed and arranged to locate any one of said connecting circuits-"whiclibecomes idle and-'- thereupon' to close)- said signaling circuit.

5. In a telephone exchange system, the combination with calling line, connecting circuits and automaticmeans for extending== said calling line toan' idle'connecti n-g circuit, of a signaling circuit including said calling line; an electromagnetic switch forclosing said signaling circuit; an operating circuit for said switch, means 'for' partially closingsaid switch operating'circuit when a predetermined number of saidconnecting circuits are busy, and am auxiliary auto matic testing means" for completing the closure of said switch operatingg circuit when- Gopiea of? tma'maintainer bei'ebtamed i101 any one of said previously busy connecting circuits becomes idle.

6. In a telephone exchange system, the combination with a' calling line, connecting circuits and autoniatic means for extending said calling line to an idle connecting circuit, of signaling circuit including said calling line, an electromagnetic switch for closing sacidcircuit, an operating circuit for said switch, an automatic non-numerical switch in the fixed contacts of which said switch operating circuit terminates, means operated when a predetermined number of saidconnectiiig circuits are busy forplacing characteristic electrical potential on the non numerical'switch contact associated with said electromagnetic switch circuit and for par tia'lly closing the operating circuit of said non-numerical switch, and auxiliary automatic means for testing said connecting circuit, said testing means being ar'anged to complete the circuit of said nou-numerical switch when a connecting circuit becomes idleand said non-numerical switch being arranged to complete the circuit of said electromagnetic switch when it encounters in its operation the contact upon which character istic electrical potential has been placed.

7. In a telephone exchange system, the combination with acalling line, a group of connecting circuits and an automatic switch for conne'cting said calling line to an idle connecting circuit in said group, of a signaling circuit including said calling line, an electromagnetic Switch for closing said signaling circuit, an operating circuit for said electro-' in'multiple so as to completethe circuit of said non-numerical switch when a connect ing circuit becomes idle, and said non-numerical switch being arranged to'complete the circuit of said electromagnetic switch when it encounters in its travel the termina associated therewith.

In" witness whereof, I hereunto subscribe my name this 29th day of November A. D., 1916';

FRANK A. LUNDQUIST.

five cents each; b d'd'ressing th ;uc issionerlefiEateats wflBhiilgtgn- .n n 

